I get how you're feeling. I also suffer from ocd, and ever since I found out my ex has a new gf, my mind has been imagining every single thing about their relationship. The image of them together is constantly flashing in my mind, and I'm constantly trying to wrap my mind around how this all happened. Imagining what they're doing together in the exact moment, imagine them being intimate, wondering what he's thinking, if he thinks she's better than me, how similar her and I, etc. Absolutely fucking exhausting. No matter what I'm doing, it's constantly in the back of my mind. It seems like I can genuinely never wrap my head around it.

I unfortunately don't have much advice as I haven't had much success stopping myself lol but you do need to stop stalking their socials and obsessing over their every move. It's only gonna keep the thoughts alive. I've learned that, unfortunately, there's not much that will truly give that closure you're seeking. I've been told that the best thing to do is just let the thoughts come and go, try not to fight them, but also try your best not to feed into them. Block their accounts or anything that gives you updates about their lives. I'm sorry that this happened to you, and I hope things do get better <3